The present invention relates generally to lubrication systems for compressors and more particularly to such systems which include means for returning oil from a compressor bearing directly to an oil sump.
Refrigeration compressors generally provide a motor drivingly connected to one end of a crankshaft rotatably journaled in a housing and have compressor means connected to the opposite end thereof. Passages are also provided in the crankshaft for supplying lubricant from an oil sump to each of the bearings supporting the crankshaft. In order to prevent slugging the compressor as well as to prevent lubricant from being carried away from the compressor and into the refrigeration system, it is desirable to direct excess lubricant supplied to the bearing away from the flowpath of the suction gas as it enters the compressing chambers. This is particularly important as regards the upper bearing in vertical crankshaft compressors which direct suction gas over the motor such as for cooling thereof as any lubricant leakage from this upper bearing into the area of the motor may be easily carried into the compressing chamber by the suction gas flowing adjacent thereto.
Various arrangements have been developed for directing excess lubricant from this upper bearing back to the oil sump, substantially all of which employ a two-piece upper bearing with some passage arrangement machined in the bearing housing which communicates with an annular space between the two upper bearing members. These passage arrangements are quite varied taking the form of inclined passages extending through the upper bearing housing or axially extending passages passing directly behind the bearing itself. In another arrangement, chevron grooves are provided on the surface of the crankshaft. While these arrangements may have varying degrees of effectiveness, they all require additional machining operations to be performed on the compressor housing and/or crankshaft which are expensive in terms of both time and labor required to set up and perform these machining operations.
Accordingly, the present invention provides a lubrication system for refrigeration compressors which includes a one-piece upper bearing having a plurality of passages provided on the work engaging surface thereof which function to effectively return excess lubricant to the oil sump. This lubricant return arrangement is substantially less costly to manufacture as it may be easily provided in the bearing during fabrication thereof. Further, it provides an effective means for returning excess lubricant from this area while also insuring that lubricant is dispersed over substantially the entire working surface of the bearing.
Additional advantages and features of the present invention will become apparent from the following description of the preferred embodiment taken in conjunction with the appended claims and the drawings.